Electrical apparatus



1929- r 1.. H. BURNHAM 1,723,839

ELECTRI CAL APPARATUS Filed Feb. 23, l928 Inventor: Locke H.Bur-nham, yW

His Attorney.

Patented Aug. 6, 1929.

* UNITED STATES PATENT OFFICE.

LOCKE H. BURNI-IAM, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERALELEC- TRIO COMPANY, A CORPORATION OF NEW YORK.

ELECTRICAL APPARATUS.

Application filed February 23, 1928. Serial No. 256,236.

My invention relates to electrical apparatus and more particularly toelectrlcal apparatus having n'iagnetic cores with vertical winding legs.In devices of this character, insulating and supporting means for thewinding or windings is necessary between the end winding turns and thecore yokes and this insulating and supporting means has been found tointerfere with efficient cooling of the end turns and the core yokes.The general ob ect of the IIIXeIlt-IOII is to provide an improvedarrangement of insulating and supporting means between the end windingturns and the core yokes.

The invention will be better understood from the following descriptiontaken in con nection with the accompanying drawing in which Fig. 1 is aview on an encased oil immersed transformer, the casing being brokenaway to show means insulating and supporting the windings in accordancewith the invention, Fig. 2 is a sectional view of the transformer on theline 22 of Fig. 1 and Fig. 8 is a sectional view on the line 3-3 of Fig.2.

Like reference characters indicate similar parts in the differentfigures of the drawing.

The transformer shown in the drawing includes a magnetic core 10 havinga vertical central winding leg, two vertical outer legs and horizontaltop and bottom yokes connecting the ends of the vertical legs. Thewinding leg is surrounded by a high voltage winding 11 and a low voltagewinding 12 so that each winding passes through the two openings orwindows between the central winding leg and the two outer legs of thecore. The axial dimension or length of each winding is somewhat lessthan the distance bet-ween the two core yokes and each end of eachwinding is spaced. from the adjacent yoke. An insulating and supportingmeans 13 for the windings is provided in each of the four spaces thusformed. Each I insulating support 13 includes a plurality of sheets orlayers 14 of suitable insulating material with interposed spacing strips15 so that spaces or ducts for the flow of a cooling medium such as oilis provided between the layers 14. The layers 14 are provided withopenings as shown in Fig.2 connecting the spaces or ducts between thelayers. It will be apparent that this arrangement provides paths for thecooling medium so that it may flow through the openings in the layers 14and the spaces between them and also along the inner surfaces of thecore yokes and the end surfaces of the windings opposite the yokes,these surfaces of the windings and yokes being thus efficiently cooled.The openings in the insulating layers 14 are staggered or offset insuccessive layers to avoid a direct path for an electrical breakdown orare between the windings and the yokes. In this way. the creepage pathbetween the windings and yokes may be so great to require a greatervoltage to break it down than would be required to puncture theinsulating layers 14 in a direct path between the windings and yokes.The insulating layers 14 preferably extend at each side beyond the facesof the core as shown most clearly in Fig. 2, the outer edge portions ofthe layers being bent away from the adjacent ends of the windings sothat they may interfere as little as possible with the flow of thecooling medium and at the same time provide insulation between thewindings and the core yokes along the two faces of the core. The coolingmedium, such oil having a high dielectric strength, in which thetransformers is immersed may be confined with the trans former in asuitable casing 16 as shown in Fig. 1.

The invention has been explained by describing and illustrating aparticular embodiment thereof but it will be apparent that variouschanges may be made without departing from the scope of the invention asdefined in the appended claims.

\Vhat I claim as new and desire to secure by Letters Patent of theUnited States, is

1. An electrical apparatus including a magnetic core having a pluralityof legs and yokes connecting the ends of said legs, a windingsurrounding one of said legs, layers of insulating material between anend of said winding and the adjacent yoke and extending beyond theadjacent portions of their surfaces, and means for spacing said layersto provide ducts between them, the layers having openings thereinconnecting said ducts, and said layers being sufficiently offset insuccessive layers to make the leak age paths between said winding andyoke longer through said openings than the shortest direct distancebetween the winding and yoke.

2. An electrical apparatus including a lU-i magnetic core having aplurality of legs and yokes connecting the ends of said legs, a windingsurrounding one of said legs, layers of insulating material between anend ofsaidwinding and the adjacent yoke, said layers extending beyondthe two faces of said core and said extended ends being bent away fromsaid Winding, and means for spacing said layers to provide ducts betweenthem, the layers having openings therein connecting said ducts.

3. An electrical. apparatus includinga magnetic core having a pluralityof legs and yokes connecting the ends of said legs,

a winding surrounding one of said legs, layers of insulating materialbetween an end of said winding and the adjacent yoke, said layersextending beyond the two faces of said core and said extended ends beingbent away from said Winding, and means for spacing said layers toprovide ducts between them, the layers having openings thereinconnecting said ducts, and said openings being offset from each other insuccessive layers.

In witness whereof, I have hereunto set my hand this 18th day ofFebruary, 1928.

LOCKE H. BURNHAM.

